Collaborative Research: IDBR: Multiscale 3-D Observation System for Analysis of Predator Prey Interactions

A unique instrumentation system will be developed that will allow simultaneous characterization of the motion of plankton, small fish, and the surrounding fluid within a complex interweaving biological and hydrodynamic environment. The system will quantify evolving three-dimensional motion of organisms and fluid over a continuous range of spatial scales spanning five orders of magnitude (from 10 centimeters down to a micron) thus enabling the simultaneous characterization of detailed behavior of small fish, zooplankton, and phytoplankton or protozoa (species of three trophic levels). The system will also have high temporal resolution down to 0.5 ms enabling the observation of rapidly occurring flow events and behavioral reactions. Two state-of-the-art velocimetry techniques will be integrated to resolve the wide range of spatial scales. Holographic velocimetry will quantify small-scale motion of organisms, microscopic appendages, and the surrounding fluid (scales 1-100 micrometer). Simultaneously, tomographic velocimetry will capture and quantify larger scales (300 micrometer - 10 cm) of motion in the volume surrounding one or multiple organisms. The system will operate in a spectral range (near-infrared) to which fish and plankton are insensitive so that the measurement system will not affect or bias their behavior. The measurements obtained from the proposed instrument would provide unprecedented quantitative observational capabilities in both spatial and temporal domains. The instrumentation will permit the study of predator-prey interactions among fish, zooplankton, ciliates, dinoflagellates, and bacteria simultaneously within realistic environments. Therefore the data captured by such a system will provide opportunities to transform understanding of interactive behavior in aquatic environments. Hence, the system will lead to new understanding of the reasons behind variations in productivity and biomass in the sea and in freshwater bodies.

Three graduate students and multiple undergraduates will be directly involved in the research. Also, the PI's will work with elementary school teachers and students at a school with significant Native American population to develop interactive projects based on understanding populations of plankton, minnows, and small fish in local freshwater environments. As part of these projects, the instrumentation system will be used to generate movies revealing detailed motion of individual species, their interactions with one another and with the surrounding flow. The resulting movies will be posted on a local website as well as on efluids.com and youtube.com.

The completed system will be available to visiting scientists for studies of the effects of hydrodynamics on behavioral and ecological interactions between organisms. Also, based on the results of this study, the PI's will maintain a web page containing a detailed plan and recommendations for development and operation of such systems by biological researchers.